Name: ………………………………………………………….
Date: ……………………………
SOLID BASICS
So what is a solid? Solids are usually hard because their molecules have been packed together.
The closer your molecules are, the harder you are. Solids also can hold their own shape. A rock
will always look like a rock unless something happens to it. The same goes for a diamond. Even
when you grind up a solid into a powder, you will see little tiny pieces of that solid under a
microscope. Liquids will move and fill up any container. Solids like their shape.
In the same way that a solid holds its shape, the atoms inside of a solid are not
allowed to move around too much. This is one of the physical characteristics of
solids. Atoms and molecules in liquids and gases are bouncing and floating
around, free to move where they want. The molecules in a solid are stuck. The
atoms still spin and the electrons fly around, but the entire atom will not change
position.
Solids can be made up of many things. They can have pure elements or a
variety of compounds inside. When you get more than one type of compound in a solid it is called a
mixture. Most rocks are mixtures of many different compounds. Concrete is a good example of a
manmade mixture.
LIQUID BASICS
The second state of matter we will discuss is a liquid. Solids are hard things you can hold. Gases
are floating around you and in bubbles. What is a liquid? Water is a liquid. Your blood is a liquid.
Liquids are an in-between state of matter. They can be found in between the solid and gas states.
They don't have to be made up of the same compounds. If you have a variety of materials in a
liquid, it is called a solution.
One characteristic of a liquid is that it will fill up the shape of a container. If you pour some water in
a cup, it will fill up the bottom of the cup first and then fill the rest. The water will also take the
shape of the cup. It fills the bottom first because of gravity. The top part of a liquid will usually have
a flat surface. That flat surface is because of gravity too. Putting an ice cube (solid) into a cup will
leave you with a cube in the middle of the cup; the shape won't change until the ice becomes a
liquid.
Another trait of liquids is that they are difficult to compress. When you compress something, you
take a certain amount and force it into a smaller space. Solids are very difficult to compress and
gases are very easy. Liquids are in the middle but tend to be difficult. When you compress
something, you force the atoms closer together. When pressure goes up, substances are
compressed. Liquids already have their atoms close together, so they are hard to compress. Many
shock absorbers in cars compress liquids in tubes.
A special force keeps liquids together. Solids are stuck together and you have to force them apart.
Gases bounce everywhere and they try to spread themselves out. Liquids
actually want to stick together. There will always be the occasional
evaporation where extra energy gets a molecule excited and the molecule
leaves the system. Overall, liquids have cohesive (sticky) forces at work that
hold the molecules together.
LOOKING FOR A GAS
Gas is everywhere. There is something called the atmosphere. That's a big layer of gas that
surrounds the Earth. Gases are random groups of atoms. In solids, atoms and molecules are
compact and close together. Liquids have atoms a little more spread out. However, gases are
really spread out and the atoms and molecules are full of energy. They are bouncing around
constantly.
Gases can fill a container of any size or shape. That is one of their physical characteristics. Think
about a balloon. No matter what shape you make the balloon it will be evenly filled with the gas
atoms. The atoms and molecules are spread equally throughout the entire balloon. Liquids can
only fill the bottom of the container while gases can fill it entirely.
You might hear the term vapour. Vapour and gas mean the same thing. The word vapour is used
to describe gases that are usually found as liquids. Good examples are water or mercury (Hg).
Compounds like carbon dioxide are usually gases at room temperature so scientists will rarely talk
about carbon dioxide vapour. Water and mercury are liquids at room temperature so they get the
vapour title.
Gases hold huge amounts of energy, and their molecules are spread out as much as possible.
With very little pressure, when compared to liquids and solids, those molecules can be
compressed. It happens all of the time. Combinations of pressure and
decreasing temperature force gases into tubes that we use every day. You
might see compressed air in a spray bottle or feel the carbon dioxide rush out of
a can of soda. Those are both examples of gas forced into a space smaller than
it would want, and the gas escapes the first chance it gets.
Information found at http://www.chem4kids.com/
Questions to ponder....
(1) List 5 things that aren’t solids. ………………………………………………………
.................................................................................................................................................
(2) Four of the following are different from the other three. Circle them and say
why they are different:
rocks
bread
milk
air
sugar
aluminium can
Different because …………………………………………………………………………...
……………………………………………………………………………………………….
(3) How are perfume and smoke similar? ………………………………………………
……………………………………………………………………………………………….
SOLIDS, LIQUIDS AND GASES- SUMMARY
SOLIDS
Can be hard
Keep their shape
Are often strong
Can be melted.
MATERIAL
LIQUIDS
Take the shape of their
container
Change shape
Flow
DECISION
GASES
Take the shape of their
container
Change shape
Particles are spread out.
DRAWING